"This paper examines the decline of mortality in Vizcaya [Spain]...the first Basque province to be industrialised at the beginning of the demographic transition.  Making use of both the death and municipal population registers we analyse its diverse trajectory in two differentiated economic environments:  those municipalities which played an important role in the industrial process and those rural municipalities which remained on the sidelines."  The author compares life expectancies, causes of death, and sanitary conditions, and discusses some social consequences of industrialization. (SUMMARY IN ENG AND FRE)