Abstract A method for long-term, reproducible observation of mature microvasculature is proposed using Sandison-Clark rabbit ear chambers. Forty-nine high-magnification (320 ×) in vivo photomicrographs, reproducible in position to a 10-μm accuracy with no overlap, are taken on each data-point day. They cover 1.617 mm 2 of vascular membrane of a standard 0.025-mm thickness. For the purpose of analysis, vessels are divided into two groups: vessels > 10 and ⩽ 10 μm in diameter. Vascular lengths and surface areas are measured directly from the photomicrographs projected at a fixed distance. These parameters are measured on Days 1, 5, 10, 20, and 30. Vascular length (> 10 μm, 8.35 mm ± 0.66; ⩽ 10 μm, 11.99 mm ± 1.31) and vascular surface area (> 10 μm, 0.168 mm 2 ± 9.88 × 10 −3; ⩽ 10 μm, 0.079 mm 2 ± 4.21 × 10 −3) obtained over a 30-day observation period indicate the reproducibility of the method. The intervascular supportive tissue area is calculated by subtracting the total microvascular surface area from the total tissue area. A dilatation factor has been derived which allows a comparison of the ratios of total microvascular surface area per unit vascular length over time. From the measured parameters, a number of important morphometric values can be calculated, e.g., vascular and supportive tissue volumes. Physiological changes are expressed as functions of masured parameters over time, with each specimen serving as its own control. These quantitative measurements are made possible by high-magnification photomicrography, which simultaneously allows qualitative analysis at the cellular level. This method should prove useful as a tool for quantitative and qualitative determination of changes in the microvasculature due to various local and systemic injuries.