The Indian gerbil,Tatera indica(Hardwicke) has been successfully maintained under laboratory conditions for 18 months, during which time over 250 vaginal cycles were recorded and 30 litters were born. Under laboratory conditions this animal had four‐to‐five‐day oestrous cycles and sterile mating induced a ten‐day pseudopregnancy. Anoestrus was not infrequent and was characterized by the absence of corpora lutea and large follicles from the ovaries and the atrophy of the uterus.The mean length of pregnancy was 22.3 days (range 18–30 days) and the litter size varied from two to seven young (mean 4.76 young). Mating at the post‐partum oestrus resulted in delayed implantation if a litter of three or more young was being suckled. Under these circumstances pregnancy lasted 36 days (range 34–40 days).Implantation was interstitial and mesometrial. The chorioallantoic placenta was discoidal, labyrinthine and haemochorial probably becoming haemoendothelial just before term.Daily injection of ovine prolactin inhibited the occurrence of oestrus and caused enlargement of the corpora lutea in three of five animals. It is suggested that prolactin might be the luteotrophic hormone in