We radio-collared a total of 29 lynx in the Swiss Jura Mountains and collected data on demography during 1988-1998. We were able to observe 10 2-14 year-old females for 32 female years. Lynx kittens were born between 12 May and 13 June (26 May ± 9 days). One female gave birth to a litter on 26 August after she had lost her first litter born in May. The average litter size was 2.00 ± 0.75 kittens (range: 1-3). The sex ratio of 1.67 females:1 male did not differ significantly from the expected ratio of 1:1. On average, 81% of adult females reproduced each year. The overall reproduction rate was 1.67 kittens/female year. Of 49 kittens, 43-49% survived until independence at the age of about 10 months. The survival rate of subadults and adults was 53 and 76%, respectively. Litter size and survival of kittens and subadults varied considerably between three observation periods, i.e. P1-P3 (P1: 1988-1991, P2: 1992-1994, P3: 1995-1997), characterised by substantial changes in the social structure of the population. During P2 only one resident male was present in the main study area, and during this period, the average litter size was lowest with 1.50 kittens only. The survival of kittens was with 37-44% lowest as well, mainly because of the high proportion of litters where all kittens were lost. However, the survival of subadults was highest during P2, when observed animals survived to adulthood. During 1974-2002, 124 mortalities were documented for the whole of the Jura Mountains. Human related mortalities were responsible for 70% of known losses. An estimation based on the radio-collared lynx suggested that poaching may have been responsible for as much as 32% of total mortality. In contrast to other study areas, traffic accidents were very important in the Jura Mountains. They might represent as much as 29% of mortality. During our 10-year study period, no significant spatial expansion of the population was recorded in Switzerland. We suppose that the high human-related mortalities limited the population, which also would explain the lack of a numerical response to an increase in prey abundance observed during the same period in the study area in Switzerland.