3,3'-Iminodipropionitrile (IDPN) has been reported to disrupt learning and memory in rats. The present work addressed the effects of IDPN on tasks requiring the use of spatial information. Separate groups of male rats were dosed with IDPN (IP, in 1 ml/kg saline) for 3 consecutive days and tested in the following procedures: (1) step-through passive avoidance conditioning (0, 100, 150, and 200 mg/kg/day); (2) Morris water maze (MWM) acquisition and retention (0, 125, 150, 175, and 200 mg/kg/day); (3) radial arm maze (RAM) acquisition (0, 100, 200, and 400 mg/kg/day); (4) RAM steady-state performance (0, 200, and 400 mg/kg/day); (5) repeated acquisition in the RAM (0, and 200 mg/kg/day). The vestibular toxicity of IDPN resulted in alterations in spontaneous behavior or swimming deficits in 5 of 8 rats treated with 175 mg/kg/day and in all the animals dosed with 200 or 400 mg/kg/day. IDPN increased step-through PA latencies at 200 mg/kg/day but not at lower doses. In the MWM, no performance deficits were observed at the dose levels preserving the swimming ability of the animals. In both the acquisition and the steady-state RAM tasks, IDPN (400 mg/kg/day) induced an increase in both choice errors and perseverative errors. In the RAM repeated acquisition paradigm, IDPN (200 mg/kg/day) induced performance deficits that included a decreased rate of within-session reduction in errors. The present data show that IDPN disrupts performance of tasks requiring spatial learning and memory and indicate that these deficits can be in part caused by an acquisition deficit. (Copyright (c) 1994 Elsevier Science Ltd.)