In rural Senegal, where mortality among children aged under 5 years is 28/1000, the Diola, a group of 220,000 people living in Casamance in Southern Senegal, perform a special ritual whenever a woman is in any of the following 3 circumstances: when 2 of her children have died early; when she has had 2 miscarriages, and when she has primary or secondary infertility. The ritual, termed "Kanaalen," is the only collective feminine ritual. It is commonly performed in villages and means and extended period of exile in an adoptive village. Thus, it is important among Diola women and makes an important impact on female migration. Yet, its social and demographic implications have not been fully appreciated in ethnological literature, except partially in 1 instance. In rural areas, a woman in any 1 of the 3 circumstances noted that threaten continuation of the lineage has no way, and probably no desire, to avoid the ritual, since social pressure is extremely compelling and to refuse would prove her own responsibility in the misfortune. The 1st step towards healing is the official attribution, by a diviner ("ajuuberew"), of the cause to an etiological agent. The death of a child could be due to the ghost of an ancestor, a soul-devouring witch, or a malign spirit. For miscarriages, only the last 2 agents can be incriminated. For infertility, witches and spirits can be responsible but suspicion focuses mostly on the evil-doing of another individual, corresponding to the classical description of a sorcerer, and the "witch" or sorcerer is generally a very close relative, possibly even the husband, and sometimes the woman herself, especially when the ritual fails. Having decided what the cause is by traditional means, the diviner treats it with specific herbal and magic remedies. Whatever the cause, he asks the woman to prepare herself for "kanaalen." The woman usually leaves her house at nightfall without telling her husband and goes to her adoptive village. The choice of the adoptive village -- usually where the woman has relatives and which has a reputation for effectiveness in Preventing infant death or miscarriage or restoring fertility -- is made by village consensus. A common situation is described in which a woman goes to her adoptive village with her newborn baby. During the years of "kanaalen," she becomes the community buffoon who always has to play the clown. Also, she must do any ridiculous task requested of her. The group also has obligations towards her: she is the guest in every house and her child is under their protection. She is punished for all wrongdoing. If the villagers fail to respect the social code, by not using her new name or by reminding her of her indignity, they have to perform a reparative ritual, at which a goat is sacrificed. When the child is ill, he is treated with herbal remedies and a ceremony is held to ward off the evil forces. When the mother is ill, there is no protecting ritual. After the child is weaned, between ages 3-5, a final ceremony is held, a final ceremony is held to untie the threads symbolizing her attachment to the altar and now symbolizing her return to a normal life. She will maintain some constraints all her life. Knowledge of how these societies try to prevent and cure illness and misfortune would be a preliminary condition for public health programs.