Introduction. The effect of Spirulina platensis on the crumb firmness during storage (96 h) of wheat bread was studied by measuring the deformation properties (total, plastic and elastic deformation). Materials and methods. Bread is obtained from wheat flour with the addition of Spirulina platensis (powder) in the amount of 2 or 4% by the weight of flour. The deformation properties of the bread crumb were studied 3, 24, 48, 72 and 96 hours after the baking. The deformation characteristics of the bread crumb are measured using automatic penetrometer, by immersion of a body with a certain mass for a certain time. Results and discussion. The highest penetration, and therefore the greatest softness of the bread crumb is found in the bread with the addition of Spirulina platensis in the amount of 4% by weight of flour. In the both algae samples, the rate of firming of the crumb is slower and after 96 hours of storage the total deformation of the crumb decreases 2.75 times, while that of control sample decreases 3.6 times. Bread samples containing Spirulina platensis have a higher plasticity of the crumb during the whole period of storage (96 hours). Algae addition in the amounts of 2% and 4% by weight of the flour leads to an improvement in the plastic properties of the bread crumb and to their retention for a longer time than in the control sample. During storage in the control sample elasticity of the bread crumb gradually decreases and at the last measurement (96 hours after baking) it is 3.54 times lower compared to the first measurement – 3 h after baking. The elasticity of the bread crumb is affected by the addition of Spirulina platensis. Bread samples, which recipe includes 4% Spirulina platensis have a higher elasticity of the crumb throughout the storage period. Conclusions. Crumb firmness decreased with the incorporation of Spirulina platensis powder. The addition of Spirulina platensis in the amount of 4% determines the greatest softness of the bread crumb.