Reproductive cycles have been studied in many species of lizards from both tropical and temperate regions (Fox, 1977; Duvall et al., 1982; Fitch, 1982; Vitt, 1982, 1986, 1992; Vitt and Goldberg, 1983; Licht, 1984; James and Shine, 1985; Whittier and Crews, 1987; Sarkar and Shivanandappa, 1989; Clerke and Alford, 1993; Shanbhag and Prasad, 1993; Flemming, 1994; Ramirez Pinilla, 1995; Huang, 1996). Lizards inhabiting temperate regions typically breed seasonally. Their gonadal development is essentially synchronous within a population, resulting in a short, well defined breeding season (Licht, 1984). Some species of lizards inhabiting the sub-tropics and tropics also breed seasonally (Licht, 1984; Vitt and Blackburn, 1991; Shanbhag and Prasad, 1993; Huang, 1996) but exhibit a longer breeding season. Though species living in the humid tropics are known to breed year round (see Licht, 1984), a few of them are seasonal breeders (Vitt and Blackburn, 1991). Among geckonids, the Javanese geckos, Cosymbotus platyrus, Hemidactylus frenatus, Peropus mutilatus, and the Australian lizard, Leiolepisma rhomboidalis are continuous breeders (Church, 1962; Wilhoft, 1963). On the other hand, H. frenatus breeds seasonally on Islands of Ryukyu Archipelago and in Taiwan (Lin and cheng, 1984; Ota, 1994). The house gecko Hemidactylus flaviviridis, is known to breed between mid-March and mid-May in northwestern India (Verma and Guraya, 1975). In south India Hemidactylus brooki is a very common household gecko, and is also encountered in Sri Lanka, Burma, Western Malaysia, and various islands in Indonesia and Philippines (Welch et al., 1990). Little is known about the reproductive biology of this lizard. Furthermore, studies on the ovarian follicular dynamics are limited to two species of geckos, Lepidodactylus lugubris and H. frenatus (Jones et al., 1978; Jones and Summers, 1984) and one species of polyautochornous (each ovary produces several eggs at a time) agamid lizard, Calotes versicolor (Shanbhag and Prasad, 1993). The present work was undertaken on H. brooki to study (1) the pattern of the female reproductive cycle, and (2) the follicular dynamics and germinal bed activity (production of oogonia and oocytes) during the ovarian cycle. Hemidactylus brooki (N = 229) were collected every fortnight from October 1992-September 1993 from households in Dharwad, Karnataka State, India (15?27'N, 75?01'E). Meteorological data were obtained from the local observatory at the University of Agricultural Sciences, Dharwad. At autopsy, snout vent length (SVL) and weights of the body, ovaries, oviducts, and liver of each lizard were recorded. In gravid lizards, the weight of oviduct along with eggs was recorded. The somatic weights were calculated by subtracting weights of the ovary and oviducts from body weights of individual lizards. The ovaries were fixed in Bouin's fluid, then dehydrated in graded series of alcohol, cleared in benzene, and embedded in paraffin. Transverse serial sections, 6p-m thick, of the right ovary, were stained with Hematoxylin-eosin. The sections were examined under 40x magnification to scan for previtellogenic, vitellogenic, and atretic (AF) follicles, and corpora lutea (CL). The diameter of the largest follicle in each ovary was measured using an ocular grid under 8x magnification. ANCOVA was performed on log transformed data of ovary, oviduct, and liver weights, with body mass as covariate and month as the class interval to exam-