Between 1836 and 1840, Jan Vilém Helfer collected thousands of insects, birds and plants in Burma, the Andaman Islands and the Mergui Archipelago, with many first records from these regions. His botanical specimens are preserved in Prague, Kew, Calcutta and many other herbaria. Yet no account has been published of his itinerary, and the volume of his collections has not previously been appreciated. We bring together the available data on Helfer, reconstruct his itinerary and the two routes by which his plants were distributed, and explain the different numbering systems used on the labels of Helfer's duplicates. Based on what his widow transferred to the Czech National Museum in Prague, Helfer collected almost 48,000 beetles, 609 bird skins, 14 mammal skins, 508 Lepidoptera, and 6,086 herbarium specimens or collections. His diaries and his wife's account of their travels have allowed us to reconstruct his itinerary, and we have generated new labels for 305 collections, most of which have two or three duplicates. Helfer's Burmese and Andaman herbarium contains some of the first records of economically important plants in which he was particularly interested.