We introduce BLINK, a new benchmark for multimodal language models (LLMs) that focuses on core visual perception abilities not found in other evaluations. Most of the BLINK tasks can be solved by humans ``within a blink'' (e.g., depth estimation, correspondence, forensics detection, and multi-view reasoning). However, we find these perception-demanding tasks cast significant challenges for current multimodal LLMs because they resist mediation through natural language. BLINK reformats 14 classic computer vision tasks into 3,978 multiple-choice questions, paired with single or multiple images and visual prompting. While humans get 95.70% accuracy on average, BLINK is surprisingly challenging for existing multimodal LLMs: even the best-performing GPT-4V and Gemini achieve accuracies of 51.32% and 45.46%, only 13.23% and 7.47% higher than random guessing, indicating that such perception abilities have not "emerged" yet in recent multimodal LLMs. Our analysis also highlights that specialist CV models could solve these problems much better, suggesting potential pathways for future improvements. We believe BLINK will stimulate the community to help multimodal LLMs catch up with human-level perception.